1. Field
The present disclosure relates to a curved piezoelectric device, and more particularly, to a curved piezoelectric device having a piezoelectric material on one surface or both surfaces of a curved substrate, where a thickness, a sectional area and a Young's modulus of the curved substrate and the piezoelectric material are controlled to locate a neutral plane in the curved substrate, thereby maximizing an electrical potential of the piezoelectric material corresponding to an external mechanical stress.
[Description about National Research and Development Support]
This study was supported by the Energy Technology R&D Project of Ministry Of Trade, Industry & Energy, Republic of Korea (Development and demonstration of Piezoelectric Energy Harvester for using unused energy in road traffic, Project No. 20142020103970) under the Industrial-Academic Cooperation Group of Hanyang University.
2. Description of the Related Art
Recently, as electronic devices become smaller, a technique capable of substituting for a battery in an electronic device is being actively studied. One of representative ways for substituting for a battery is using a piezoelectric element. In other words, a piezoelectric element may be disposed in an electronic device, mechanical energy such as pressure, vibration or the like may be converted into electric energy by means of the piezoelectric element, and the electric energy generated by the piezoelectric element may be used as a power source of the electronic device.
The piezoelectric element may be classified into a bulk type, a cantilever type, a flexible type or the like, depending on its shape and the kind of piezoelectric material. In a bulk type, a mechanical force is applied to a bulk type piezoelectric material to generate electric energy. In a cantilever type, a piezoelectric material is attached to one side of a cantilever type support to generate electric energy according to deformation of the support. In a flexible type, a mechanical force is applied to a flexible piezoelectric material to generate electric energy. Korean Patent Registration No. 10-599083 discloses an example of the cantilever type piezoelectric element.
In an existing piezoelectric element as described above, a bulk type piezoelectric element may not easily apply a great strain due to weak brittleness, and a cantilever type piezoelectric element may not be easily applied to a small electronic device due to a large volume since it demands additional structures such as a holder, a stopper or the like. In addition, a flexible type piezoelectric element using a flexible piezoelectric material has a very small output energy obtained by applying a mechanical force.